/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * VLAN         An implementation of 802.1Q VLAN tagging.
 *
 * Authors:     Ben Greear <greearb@candelatech.com>
 */
#ifndef _LINUX_IF_VLAN_H_
#define _LINUX_IF_VLAN_H_

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/bug.h>
#include <uapi/linux/if_vlan.h>

#define VLAN_HLEN       4               /* The additional bytes required by VLAN
                                         * (in addition to the Ethernet header)
                                         */
#define VLAN_ETH_HLEN   18              /* Total octets in header.       */
#define VLAN_ETH_ZLEN   64              /* Min. octets in frame sans FCS */

/*
 * According to 802.3ac, the packet can be 4 bytes longer. --Klika Jan
 */
#define VLAN_ETH_DATA_LEN       1500    /* Max. octets in payload        */
#define VLAN_ETH_FRAME_LEN      1518    /* Max. octets in frame sans FCS */

#define VLAN_MAX_DEPTH  8               /* Max. number of nested VLAN tags parsed */

/*
 *      struct vlan_hdr - vlan header
 *      @h_vlan_TCI: priority and VLAN ID
 *      @h_vlan_encapsulated_proto: packet type ID or len
 */
struct vlan_hdr {
        __be16  h_vlan_TCI;
        __be16  h_vlan_encapsulated_proto;
};

/**
 *      struct vlan_ethhdr - vlan ethernet header (ethhdr + vlan_hdr)
 *      @h_dest: destination ethernet address
 *      @h_source: source ethernet address
 *      @h_vlan_proto: ethernet protocol
 *      @h_vlan_TCI: priority and VLAN ID
 *      @h_vlan_encapsulated_proto: packet type ID or len
 */
struct vlan_ethhdr {
        struct_group(addrs,
                unsigned char   h_dest[ETH_ALEN];
                unsigned char   h_source[ETH_ALEN];
        );
        __be16          h_vlan_proto;
        __be16          h_vlan_TCI;
        __be16          h_vlan_encapsulated_proto;
};

#include <linux/skbuff.h>

static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
{
        return (struct vlan_ethhdr *)skb_mac_header(skb);
}

/* Prefer this version in TX path, instead of
 * skb_reset_mac_header() + vlan_eth_hdr()
 */
static inline struct vlan_ethhdr *skb_vlan_eth_hdr(const struct sk_buff *skb)
{
        return (struct vlan_ethhdr *)skb->data;
}

#define VLAN_PRIO_MASK          0xe000 /* Priority Code Point */
#define VLAN_PRIO_SHIFT         13
#define VLAN_CFI_MASK           0x1000 /* Canonical Format Indicator / Drop Eligible Indicator */
#define VLAN_VID_MASK           0x0fff /* VLAN Identifier */
#define VLAN_N_VID              4096

/* found in socket.c */
extern void vlan_ioctl_set(int (*hook)(struct net *, void __user *));

#define skb_vlan_tag_present(__skb)     (!!(__skb)->vlan_all)
#define skb_vlan_tag_get(__skb)         ((__skb)->vlan_tci)
#define skb_vlan_tag_get_id(__skb)      ((__skb)->vlan_tci & VLAN_VID_MASK)
#define skb_vlan_tag_get_cfi(__skb)     (!!((__skb)->vlan_tci & VLAN_CFI_MASK))
#define skb_vlan_tag_get_prio(__skb)    (((__skb)->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT)

static inline int vlan_get_rx_ctag_filter_info(struct net_device *dev)
{
        ASSERT_RTNL();
        return notifier_to_errno(call_netdevice_notifiers(NETDEV_CVLAN_FILTER_PUSH_INFO, dev));
}

static inline void vlan_drop_rx_ctag_filter_info(struct net_device *dev)
{
        ASSERT_RTNL();
        call_netdevice_notifiers(NETDEV_CVLAN_FILTER_DROP_INFO, dev);
}

static inline int vlan_get_rx_stag_filter_info(struct net_device *dev)
{
        ASSERT_RTNL();
        return notifier_to_errno(call_netdevice_notifiers(NETDEV_SVLAN_FILTER_PUSH_INFO, dev));
}

static inline void vlan_drop_rx_stag_filter_info(struct net_device *dev)
{
        ASSERT_RTNL();
        call_netdevice_notifiers(NETDEV_SVLAN_FILTER_DROP_INFO, dev);
}

/**
 *      struct vlan_pcpu_stats - VLAN percpu rx/tx stats
 *      @rx_packets: number of received packets
 *      @rx_bytes: number of received bytes
 *      @rx_multicast: number of received multicast packets
 *      @tx_packets: number of transmitted packets
 *      @tx_bytes: number of transmitted bytes
 *      @syncp: synchronization point for 64bit counters
 *      @rx_errors: number of rx errors
 *      @tx_dropped: number of tx drops
 */
struct vlan_pcpu_stats {
        u64_stats_t             rx_packets;
        u64_stats_t             rx_bytes;
        u64_stats_t             rx_multicast;
        u64_stats_t             tx_packets;
        u64_stats_t             tx_bytes;
        struct u64_stats_sync   syncp;
        u32                     rx_errors;
        u32                     tx_dropped;
};

#if IS_ENABLED(CONFIG_VLAN_8021Q)

extern struct net_device *__vlan_find_dev_deep_rcu(struct net_device *real_dev,
                                               __be16 vlan_proto, u16 vlan_id);
extern int vlan_for_each(struct net_device *dev,
                         int (*action)(struct net_device *dev, int vid,
                                       void *arg), void *arg);
extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
extern u16 vlan_dev_vlan_id(const struct net_device *dev);
extern __be16 vlan_dev_vlan_proto(const struct net_device *dev);

/**
 *      struct vlan_priority_tci_mapping - vlan egress priority mappings
 *      @priority: skb priority
 *      @vlan_qos: vlan priority: (skb->priority << 13) & 0xE000
 *      @next: pointer to next struct
 */
struct vlan_priority_tci_mapping {
        u32                                     priority;
        u16                                     vlan_qos;
        struct vlan_priority_tci_mapping        *next;
};

struct proc_dir_entry;
struct netpoll;

/**
 *      struct vlan_dev_priv - VLAN private device data
 *      @nr_ingress_mappings: number of ingress priority mappings
 *      @ingress_priority_map: ingress priority mappings
 *      @nr_egress_mappings: number of egress priority mappings
 *      @egress_priority_map: hash of egress priority mappings
 *      @vlan_proto: VLAN encapsulation protocol
 *      @vlan_id: VLAN identifier
 *      @flags: device flags
 *      @real_dev: underlying netdevice
 *      @dev_tracker: refcount tracker for @real_dev reference
 *      @real_dev_addr: address of underlying netdevice
 *      @dent: proc dir entry
 *      @vlan_pcpu_stats: ptr to percpu rx stats
 *      @netpoll: netpoll instance "propagated" down to @real_dev
 */
struct vlan_dev_priv {
        unsigned int                            nr_ingress_mappings;
        u32                                     ingress_priority_map[8];
        unsigned int                            nr_egress_mappings;
        struct vlan_priority_tci_mapping        *egress_priority_map[16];

        __be16                                  vlan_proto;
        u16                                     vlan_id;
        u16                                     flags;

        struct net_device                       *real_dev;
        netdevice_tracker                       dev_tracker;

        unsigned char                           real_dev_addr[ETH_ALEN];

        struct proc_dir_entry                   *dent;
        struct vlan_pcpu_stats __percpu         *vlan_pcpu_stats;
#ifdef CONFIG_NET_POLL_CONTROLLER
        struct netpoll                          *netpoll;
#endif
};

static inline bool is_vlan_dev(const struct net_device *dev)
{
        return dev->priv_flags & IFF_802_1Q_VLAN;
}

static inline struct vlan_dev_priv *vlan_dev_priv(const struct net_device *dev)
{
        return netdev_priv(dev);
}

static inline u16
vlan_dev_get_egress_qos_mask(struct net_device *dev, u32 skprio)
{
        struct vlan_priority_tci_mapping *mp;

        smp_rmb(); /* coupled with smp_wmb() in vlan_dev_set_egress_priority() */

        mp = vlan_dev_priv(dev)->egress_priority_map[(skprio & 0xF)];
        while (mp) {
                if (mp->priority == skprio) {
                        return mp->vlan_qos; /* This should already be shifted
                                              * to mask correctly with the
                                              * VLAN's TCI */
                }
                mp = mp->next;
        }
        return 0;
}

extern bool vlan_do_receive(struct sk_buff **skb);

extern int vlan_vid_add(struct net_device *dev, __be16 proto, u16 vid);
extern void vlan_vid_del(struct net_device *dev, __be16 proto, u16 vid);

extern int vlan_vids_add_by_dev(struct net_device *dev,
                                const struct net_device *by_dev);
extern void vlan_vids_del_by_dev(struct net_device *dev,
                                 const struct net_device *by_dev);

extern bool vlan_uses_dev(const struct net_device *dev);

#else
static inline bool is_vlan_dev(const struct net_device *dev)
{
        return false;
}

static inline struct net_device *
__vlan_find_dev_deep_rcu(struct net_device *real_dev,
                     __be16 vlan_proto, u16 vlan_id)
{
        return NULL;
}

static inline int
vlan_for_each(struct net_device *dev,
              int (*action)(struct net_device *dev, int vid, void *arg),
              void *arg)
{
        return 0;
}

static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
{
        WARN_ON_ONCE(1);
        return NULL;
}

static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
{
        WARN_ON_ONCE(1);
        return 0;
}

static inline __be16 vlan_dev_vlan_proto(const struct net_device *dev)
{
        WARN_ON_ONCE(1);
        return 0;
}

static inline u16 vlan_dev_get_egress_qos_mask(struct net_device *dev,
                                               u32 skprio)
{
        return 0;
}

static inline bool vlan_do_receive(struct sk_buff **skb)
{
        return false;
}

static inline int vlan_vid_add(struct net_device *dev, __be16 proto, u16 vid)
{
        return 0;
}

static inline void vlan_vid_del(struct net_device *dev, __be16 proto, u16 vid)
{
}

static inline int vlan_vids_add_by_dev(struct net_device *dev,
                                       const struct net_device *by_dev)
{
        return 0;
}

static inline void vlan_vids_del_by_dev(struct net_device *dev,
                                        const struct net_device *by_dev)
{
}

static inline bool vlan_uses_dev(const struct net_device *dev)
{
        return false;
}
#endif

/**
 * eth_type_vlan - check for valid vlan ether type.
 * @ethertype: ether type to check
 *
 * Returns: true if the ether type is a vlan ether type.
 */
static inline bool eth_type_vlan(__be16 ethertype)
{
        switch (ethertype) {
        case htons(ETH_P_8021Q):
        case htons(ETH_P_8021AD):
                return true;
        default:
                return false;
        }
}

static inline bool vlan_hw_offload_capable(netdev_features_t features,
                                           __be16 proto)
{
        if (proto == htons(ETH_P_8021Q) && features & NETIF_F_HW_VLAN_CTAG_TX)
                return true;
        if (proto == htons(ETH_P_8021AD) && features & NETIF_F_HW_VLAN_STAG_TX)
                return true;
        return false;
}

/**
 * __vlan_insert_inner_tag - inner VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_proto: VLAN encapsulation protocol
 * @vlan_tci: VLAN TCI to insert
 * @mac_len: MAC header length including outer vlan headers
 *
 * Inserts the VLAN tag into @skb as part of the payload at offset mac_len
 * Does not change skb->protocol so this function can be used during receive.
 *
 * Returns: error if skb_cow_head fails.
 */
static inline int __vlan_insert_inner_tag(struct sk_buff *skb,
                                          __be16 vlan_proto, u16 vlan_tci,
                                          unsigned int mac_len)
{
        const u8 meta_len = mac_len > ETH_TLEN ? skb_metadata_len(skb) : 0;
        struct vlan_ethhdr *veth;

        if (skb_cow_head(skb, meta_len + VLAN_HLEN) < 0)
                return -ENOMEM;

        skb_push(skb, VLAN_HLEN);

        /* Move the mac header sans proto to the beginning of the new header. */
        if (likely(mac_len > ETH_TLEN))
                skb_postpush_data_move(skb, VLAN_HLEN, mac_len - ETH_TLEN);
        if (skb_mac_header_was_set(skb))
                skb->mac_header -= VLAN_HLEN;

        veth = (struct vlan_ethhdr *)(skb->data + mac_len - ETH_HLEN);

        /* first, the ethernet type */
        if (likely(mac_len >= ETH_TLEN)) {
                /* h_vlan_encapsulated_proto should already be populated, and
                 * skb->data has space for h_vlan_proto
                 */
                veth->h_vlan_proto = vlan_proto;
        } else {
                /* h_vlan_encapsulated_proto should not be populated, and
                 * skb->data has no space for h_vlan_proto
                 */
                veth->h_vlan_encapsulated_proto = skb->protocol;
        }

        /* now, the TCI */
        veth->h_vlan_TCI = htons(vlan_tci);

        return 0;
}

/**
 * __vlan_insert_tag - regular VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_proto: VLAN encapsulation protocol
 * @vlan_tci: VLAN TCI to insert
 *
 * Inserts the VLAN tag into @skb as part of the payload
 * Does not change skb->protocol so this function can be used during receive.
 *
 * Returns: error if skb_cow_head fails.
 */
static inline int __vlan_insert_tag(struct sk_buff *skb,
                                    __be16 vlan_proto, u16 vlan_tci)
{
        return __vlan_insert_inner_tag(skb, vlan_proto, vlan_tci, ETH_HLEN);
}

/**
 * vlan_insert_inner_tag - inner VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_proto: VLAN encapsulation protocol
 * @vlan_tci: VLAN TCI to insert
 * @mac_len: MAC header length including outer vlan headers
 *
 * Inserts the VLAN tag into @skb as part of the payload at offset mac_len
 * Returns a VLAN tagged skb. This might change skb->head.
 *
 * Following the skb_unshare() example, in case of error, the calling function
 * doesn't have to worry about freeing the original skb.
 *
 * Does not change skb->protocol so this function can be used during receive.
 *
 * Return: modified @skb on success, NULL on error (@skb is freed).
 */
static inline struct sk_buff *vlan_insert_inner_tag(struct sk_buff *skb,
                                                    __be16 vlan_proto,
                                                    u16 vlan_tci,
                                                    unsigned int mac_len)
{
        int err;

        err = __vlan_insert_inner_tag(skb, vlan_proto, vlan_tci, mac_len);
        if (err) {
                dev_kfree_skb_any(skb);
                return NULL;
        }
        return skb;
}

/**
 * vlan_insert_tag - regular VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_proto: VLAN encapsulation protocol
 * @vlan_tci: VLAN TCI to insert
 *
 * Inserts the VLAN tag into @skb as part of the payload
 * Returns a VLAN tagged skb. This might change skb->head.
 *
 * Following the skb_unshare() example, in case of error, the calling function
 * doesn't have to worry about freeing the original skb.
 *
 * Does not change skb->protocol so this function can be used during receive.
 *
 * Return: modified @skb on success, NULL on error (@skb is freed).
 */
static inline struct sk_buff *vlan_insert_tag(struct sk_buff *skb,
                                              __be16 vlan_proto, u16 vlan_tci)
{
        return vlan_insert_inner_tag(skb, vlan_proto, vlan_tci, ETH_HLEN);
}

/**
 * vlan_insert_tag_set_proto - regular VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_proto: VLAN encapsulation protocol
 * @vlan_tci: VLAN TCI to insert
 *
 * Inserts the VLAN tag into @skb as part of the payload
 * Returns a VLAN tagged skb. This might change skb->head.
 *
 * Following the skb_unshare() example, in case of error, the calling function
 * doesn't have to worry about freeing the original skb.
 *
 * Return: modified @skb on success, NULL on error (@skb is freed).
 */
static inline struct sk_buff *vlan_insert_tag_set_proto(struct sk_buff *skb,
                                                        __be16 vlan_proto,
                                                        u16 vlan_tci)
{
        skb = vlan_insert_tag(skb, vlan_proto, vlan_tci);
        if (skb)
                skb->protocol = vlan_proto;
        return skb;
}

/**
 * __vlan_hwaccel_clear_tag - clear hardware accelerated VLAN info
 * @skb: skbuff to clear
 *
 * Clears the VLAN information from @skb
 */
static inline void __vlan_hwaccel_clear_tag(struct sk_buff *skb)
{
        skb->vlan_all = 0;
}

/**
 * __vlan_hwaccel_copy_tag - copy hardware accelerated VLAN info from another skb
 * @dst: skbuff to copy to
 * @src: skbuff to copy from
 *
 * Copies VLAN information from @src to @dst (for branchless code)
 */
static inline void __vlan_hwaccel_copy_tag(struct sk_buff *dst, const struct sk_buff *src)
{
        dst->vlan_all = src->vlan_all;
}

/*
 * __vlan_hwaccel_push_inside - pushes vlan tag to the payload
 * @skb: skbuff to tag
 *
 * Pushes the VLAN tag from @skb->vlan_tci inside to the payload.
 *
 * Following the skb_unshare() example, in case of error, the calling function
 * doesn't have to worry about freeing the original skb.
 */
static inline struct sk_buff *__vlan_hwaccel_push_inside(struct sk_buff *skb)
{
        skb = vlan_insert_tag_set_proto(skb, skb->vlan_proto,
                                        skb_vlan_tag_get(skb));
        if (likely(skb))
                __vlan_hwaccel_clear_tag(skb);
        return skb;
}

/**
 * __vlan_hwaccel_put_tag - hardware accelerated VLAN inserting
 * @skb: skbuff to tag
 * @vlan_proto: VLAN encapsulation protocol
 * @vlan_tci: VLAN TCI to insert
 *
 * Puts the VLAN TCI in @skb->vlan_tci and lets the device do the rest
 */
static inline void __vlan_hwaccel_put_tag(struct sk_buff *skb,
                                          __be16 vlan_proto, u16 vlan_tci)
{
        skb->vlan_proto = vlan_proto;
        skb->vlan_tci = vlan_tci;
}

/**
 * __vlan_get_tag - get the VLAN ID that is part of the payload
 * @skb: skbuff to query
 * @vlan_tci: buffer to store value
 *
 * Returns: error if the skb is not of VLAN type
 */
static inline int __vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
{
        struct vlan_ethhdr *veth = skb_vlan_eth_hdr(skb);

        if (!eth_type_vlan(veth->h_vlan_proto))
                return -ENODATA;

        *vlan_tci = ntohs(veth->h_vlan_TCI);
        return 0;
}

/**
 * __vlan_hwaccel_get_tag - get the VLAN ID that is in @skb->cb[]
 * @skb: skbuff to query
 * @vlan_tci: buffer to store value
 *
 * Returns: error if @skb->vlan_tci is not set correctly
 */
static inline int __vlan_hwaccel_get_tag(const struct sk_buff *skb,
                                         u16 *vlan_tci)
{
        if (skb_vlan_tag_present(skb)) {
                *vlan_tci = skb_vlan_tag_get(skb);
                return 0;
        } else {
                *vlan_tci = 0;
                return -ENODATA;
        }
}

/**
 * vlan_get_tag - get the VLAN ID from the skb
 * @skb: skbuff to query
 * @vlan_tci: buffer to store value
 *
 * Returns: error if the skb is not VLAN tagged
 */
static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
{
        if (skb->dev->features & NETIF_F_HW_VLAN_CTAG_TX) {
                return __vlan_hwaccel_get_tag(skb, vlan_tci);
        } else {
                return __vlan_get_tag(skb, vlan_tci);
        }
}

struct vlan_type_depth {
        __be16 type;
        u16 depth;
};

struct vlan_type_depth __vlan_get_protocol_offset(const struct sk_buff *skb,
                                                  __be16 type,
                                                  int mac_offset);

/**
 * vlan_get_protocol_offset_inline() - get protocol EtherType.
 * @skb: skbuff to query
 * @type: first vlan protocol
 * @mac_offset: MAC offset
 * @depth: buffer to store length of eth and vlan tags in bytes
 *
 * Returns: the EtherType of the packet, regardless of whether it is
 * vlan encapsulated (normal or hardware accelerated) or not.
 */
static inline
__be16 vlan_get_protocol_offset_inline(const struct sk_buff *skb,
                                       __be16 type,
                                       int mac_offset,
                                       int *depth)
{
        if (eth_type_vlan(type)) {
                struct vlan_type_depth res;

                res = __vlan_get_protocol_offset(skb, type, mac_offset);

                if (depth && res.type)
                        *depth = res.depth;
                return res.type;
        }

        if (depth)
                *depth = skb->mac_len;

        return type;
}

static inline __be16 __vlan_get_protocol(const struct sk_buff *skb, __be16 type,
                                         int *depth)
{
        return vlan_get_protocol_offset_inline(skb, type, 0, depth);
}

/**
 * vlan_get_protocol - get protocol EtherType.
 * @skb: skbuff to query
 *
 * Returns: the EtherType of the packet, regardless of whether it is
 * vlan encapsulated (normal or hardware accelerated) or not.
 */
static inline __be16 vlan_get_protocol(const struct sk_buff *skb)
{
        return __vlan_get_protocol(skb, skb->protocol, NULL);
}

/* This version of __vlan_get_protocol() also pulls mac header in skb->head */
static inline __be16 vlan_get_protocol_and_depth(struct sk_buff *skb,
                                                 __be16 type, int *depth)
{
        int maclen;

        type = __vlan_get_protocol(skb, type, &maclen);

        if (type) {
                if (!pskb_may_pull(skb, maclen))
                        type = 0;
                else if (depth)
                        *depth = maclen;
        }
        return type;
}

/* A getter for the SKB protocol field which will handle VLAN tags consistently
 * whether VLAN acceleration is enabled or not.
 */
static inline __be16 skb_protocol(const struct sk_buff *skb, bool skip_vlan)
{
        if (!skip_vlan)
                /* VLAN acceleration strips the VLAN header from the skb and
                 * moves it to skb->vlan_proto
                 */
                return skb_vlan_tag_present(skb) ? skb->vlan_proto : skb->protocol;

        return vlan_get_protocol(skb);
}

static inline void vlan_set_encap_proto(struct sk_buff *skb,
                                        struct vlan_hdr *vhdr)
{
        __be16 proto;
        unsigned short *rawp;

        /*
         * Was a VLAN packet, grab the encapsulated protocol, which the layer
         * three protocols care about.
         */

        proto = vhdr->h_vlan_encapsulated_proto;
        if (eth_proto_is_802_3(proto)) {
                skb->protocol = proto;
                return;
        }

        rawp = (unsigned short *)(vhdr + 1);
        if (*rawp == 0xFFFF)
                /*
                 * This is a magic hack to spot IPX packets. Older Novell
                 * breaks the protocol design and runs IPX over 802.3 without
                 * an 802.2 LLC layer. We look for FFFF which isn't a used
                 * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
                 * but does for the rest.
                 */
                skb->protocol = htons(ETH_P_802_3);
        else
                /*
                 * Real 802.2 LLC
                 */
                skb->protocol = htons(ETH_P_802_2);
}

/**
 * vlan_remove_tag - remove outer VLAN tag from payload
 * @skb: skbuff to remove tag from
 * @vlan_tci: buffer to store value
 *
 * Expects the skb to contain a VLAN tag in the payload, and to have skb->data
 * pointing at the MAC header.
 */
static inline void vlan_remove_tag(struct sk_buff *skb, u16 *vlan_tci)
{
        struct vlan_hdr *vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);

        *vlan_tci = ntohs(vhdr->h_vlan_TCI);

        vlan_set_encap_proto(skb, vhdr);
        __skb_pull(skb, VLAN_HLEN);
        skb_postpull_data_move(skb, VLAN_HLEN, 2 * ETH_ALEN);
}

/**
 * skb_vlan_tagged - check if skb is vlan tagged.
 * @skb: skbuff to query
 *
 * Returns: true if the skb is tagged, regardless of whether it is hardware
 * accelerated or not.
 */
static inline bool skb_vlan_tagged(const struct sk_buff *skb)
{
        if (!skb_vlan_tag_present(skb) &&
            likely(!eth_type_vlan(skb->protocol)))
                return false;

        return true;
}

/**
 * skb_vlan_tagged_multi - check if skb is vlan tagged with multiple headers.
 * @skb: skbuff to query
 *
 * Returns: true if the skb is tagged with multiple vlan headers, regardless
 * of whether it is hardware accelerated or not.
 */
static inline bool skb_vlan_tagged_multi(struct sk_buff *skb)
{
        __be16 protocol = skb->protocol;

        if (!skb_vlan_tag_present(skb)) {
                struct vlan_ethhdr *veh;

                if (likely(!eth_type_vlan(protocol)))
                        return false;

                if (unlikely(!pskb_may_pull(skb, VLAN_ETH_HLEN)))
                        return false;

                veh = skb_vlan_eth_hdr(skb);
                protocol = veh->h_vlan_encapsulated_proto;
        }

        if (!eth_type_vlan(protocol))
                return false;

        return true;
}

/**
 * vlan_features_check - drop unsafe features for skb with multiple tags.
 * @skb: skbuff to query
 * @features: features to be checked
 *
 * Returns: features without unsafe ones if the skb has multiple tags.
 */
static inline netdev_features_t vlan_features_check(struct sk_buff *skb,
                                                    netdev_features_t features)
{
        if (skb_vlan_tagged_multi(skb)) {
                /* In the case of multi-tagged packets, use a direct mask
                 * instead of using netdev_interesect_features(), to make
                 * sure that only devices supporting NETIF_F_HW_CSUM will
                 * have checksum offloading support.
                 */
                features &= NETIF_F_SG | NETIF_F_HIGHDMA | NETIF_F_HW_CSUM |
                            NETIF_F_FRAGLIST | NETIF_F_HW_VLAN_CTAG_TX |
                            NETIF_F_HW_VLAN_STAG_TX;
        }

        return features;
}

/**
 * compare_vlan_header - Compare two vlan headers
 * @h1: Pointer to vlan header
 * @h2: Pointer to vlan header
 *
 * Compare two vlan headers.
 *
 * Please note that alignment of h1 & h2 are only guaranteed to be 16 bits.
 *
 * Return: 0 if equal, arbitrary non-zero value if not equal.
 */
static inline unsigned long compare_vlan_header(const struct vlan_hdr *h1,
                                                const struct vlan_hdr *h2)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
        return *(u32 *)h1 ^ *(u32 *)h2;
#else
        return ((__force u32)h1->h_vlan_TCI ^ (__force u32)h2->h_vlan_TCI) |
               ((__force u32)h1->h_vlan_encapsulated_proto ^
                (__force u32)h2->h_vlan_encapsulated_proto);
#endif
}
#endif /* !(_LINUX_IF_VLAN_H_) */